This application is a competitive renewal of the UCLA Center for Advancing Longitudinal Drug Abuse Research (CALDAR; P30DA016383) funded by NIDA since September 2005. The overarching mission of CALDAR is to promote and support rigorous longitudinal research to enhance scientific understanding of how drug use patterns evolve and interplay with HIV, drug treatment services, and other service systems (e.g., criminal justice, mental health) over time. Building upon the life course drug use framework and considerable empirical examinations of drug use trajectories and related HIV risk, mental health, and criminal involvement, during this renewal period the Center's theme will focus on recovery from drug dependence. To support the Center's mission, thematic focus on recovery, and research projects, CALDAR comprises three Cores: (1) the Coordination & Integration Core will provide overall Center leadership, administrative support, coordination across Cores, and support for the pilot project program; (2) the Research & Methods Support Core will identify priorities for longitudinal research on drug abuse and recovery and will enhance the quality of attendant methodological procedures and approaches; and (3) the Statistical Support & Analysis Core will support longitudinal statistical applications and analyses. All Cores will be involved in CALDAR's education, mentoring, and training activities. The chronic nature of drug dependence necessitates a longitudinal approach to better understand and address addiction and to promote recovery. Given the complexity of conducting quality longitudinal studies, the rapid development of longitudinal statistical modeling techniques, and the challenges in analyzing longitudinal data, the Center's infrastructure greatly enhances the efficiency and quality of Center-affiliated projects, resulting in enhanced capacity to conduct and integrate longitudinal research projects and address recovery-related issues. CALDAR serves a crucial role as a national resource for advancing longitudinal research on drug abuse and recovery via its scientific findings and dissemination, data sharing, education and training, and support of emerging investigators.